This application claims the priority of German application 197 56 018.0, filed Dec. 17, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a device for supplying pressure medium and/or lubricant to at least one hydraulic consumer in an internal combustion engine and including features to remove air from the pressure medium and/or lubricants.
In preferred embodiments of the invention, the air removing features are disposed in a pressure line from a pressure medium source or supply tank to the hydraulic consumer.
A device of this general kind is known for example from German Patent Document DE 36 23 238 C2. This document describes a pressure medium supply for hydraulic valve play compensating elements of an internal combustion engine which are to be supplied with essentially air-free oil from the lubricating oil circuit. The air is removed from the oil using a cyclone air separator located on the pressure side between the oil pump and the hydraulic consumer. To effectively remove the air from the oil, cyclone air separators, because of their operating principle, must have flow passing through them at relatively high flowrates or flow volumes. For this purpose, a description is provided in this document that says that in addition to the connection for the hydraulic valve play compensating element, at least one connection for additional lubricant consumers is provided. These consumers are for example designed as spray nozzles for supplying the lubricant to the sliding surfaces of the cams. A sufficient flowrate and/or a sufficient lubricant throughput in the cyclone air separator is guaranteed through these consumers with a relatively high lubricant throughput, making removal of the air from the oil possible.
On the contrary, a goal of the invention is to improve devices of the above-described kind for supplying pressure medium and/or lubricant to at least one hydraulic consumer in an internal combustion engine by virtue of the fact that effective removal of the air on the pressure side is possible even at low volume flows. Moreover this device is intended to be used in pressure-controlled or pressure-regulated consumers.
This goal is achieved according to the invention by removing the air utilizing an expansion chamber that has a valve controlled connection to the supply tank. By providing an expansion chamber in the pressure line to the consumer, which has a valve-controlled connection to the supply tank, removal of air from the oil can be guaranteed even at low flowrates and/or low flow volumes. By locating this expansion chamber in the pressure line, a local reduction of the flowrate is achieved that improves the removal of the air from the air-oil mixture. This arrangement is also especially simple in design and consequently can be manufactured economically. In addition this device according to the invention has the advantage that it takes up only a small amount of extra space.
Removal of the air from the oil delivered to the consumer is especially effective if the valve-controlled connection between the expansion chamber and the supply tank is located at least approximately in the vicinity of the point in this expansion chamber that is geodetically highest in the installed or operating position. As a result of this spatial arrangement, removal of the air from the oil by outgassing the air dissolved in the oil is significantly improved.
The valve-controlled connection between the expansion chamber and the supply tank can thus be designed in an especially simple, economical, and effective manner in the form of a ball valve with a conical valve seat. A valve of this kind is especially simple and economical to manufacture and is also functional in the long term, even under the operating conditions that prevail in internal combustion engines.
Especially effective removal of the air from the oil takes place if the valve ball is designed according to certain preferred embodiments with play in a correspondingly designed section of the connecting line to the supply tank. The dimensions of the valve ball and the receiving section of the connecting line are adjusted to one another in an advantageous manner in such fashion that a specific gap is set between the valve ball and the connecting line portion provided the valve ball does not abut the valve seat. The dimensions of the valve member and the receiving portion of the connecting line are adjusted to one another in such fashion that the valve member is guided with play, so that air can flow through the annular gap while the passage of oil at this point is largely prevented.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.